Coil anchor strip and method of using



Feb. 6, 1968 I E. c. RECHEL' 3,368,176-

COIL ANCHOR STRIP AND METHOD OF USING Filed Nov. 25, 1966 Val/ H24 ImI 2 INVENTOR: EDWIN C. RECHEL ATT'YS United States Patent Ofiice 3,368,176 COIL ANCHOR STRIP AND METHOD OF USING Edwin C. Rechel, 85 Lancaster Road, Shirley, Mass. 01464 Continuation-impart of application Ser. No. 519,288,

Jan. 7, 1966, which is a continuation-in-part of application Ser. No. 353,774, Mar. 23, 1964. This application Nov. 25, 1966, Ser. No. 596,958

Claims. (Cl. 336192) This application is a continua'tion-in-part of my copending application, Ser. No. 519,288, now abandoned, filed Jan. 7, 1966, which was a continuation-in-part of my application Ser. No. 353,774, now abandoned, filed Mar. 23, 1964.

This invention relates to a coil anchor strip and method of using, and, more particularly, to a strip having novel cut-outs of generally L-shaped configuration which facilitate removing the inner and outer leads from wound fllectrical coils such as inductances, transformers and the The invention is an improvement over US Patent No. 2,122,894, issued July 5, 1958. That patent discloses a strip which must be used in pairs and which aids in obtaining an intermediate tap of wound coil. Not only must the strip disclosed in Patent 2,122,894 be used in pairs, but extreme care must be used in removing the intermediate turns which provide the tap so that the wire is not pulled in such a manner as to rupture the strips. In addition, the strip described in the patent may not be used to provide an inner or outer lead to the coil, but may be used only for an intermediate tap. The prior art method of providing the inner and outer leads calls for elaborate taping operations as the coil is wound. The taping operation is not only time consuming, if performed by hand, or expensive, if performed mechanically by complex machinery, but also the character of the tape makes transverse sawing of the coil forms on which the coil is wound diflicult. In addition, this invention provides a unique method of using the coil form in developing advantageously accessible marginal turns for the lead which also constitutes an improvement over the prior art method of winding.

It is, therefore, an object of the invention to provide a structure and method for use in obtaining inner leads of wound electrical coil without having to anchor the turns of the coil with tape or other adhesive. Further objects and advantages of the invention will be apparent as the specification proceeds.

The invention is explained in conjunction with the accompanying drawing in which:

FIG. 1 is a fragmentary perspective view of a coil form in the process of being wound with conductor wire;

FIG. 2 is a fragmentary plan view of the inventive anchor strip; and

FIG. 3 is a fragmentary sectional view of the completed coil and corresponds to a view taken along the line 33 of the incomplete coil form of FIG. 1.

In the illustration given and with reference to FIG. 1, the numeral designates generally a coil form which is seen to be square in cross-section and constructed of dielectric kraft or like coil form material of construction. The form may be advantageously spirally wound utilizing the apparatus seen in Patent Re. No. 25,820. The showing of FIG. 1 is of a coil in the initial stages of being wound wherein an insulated conductor wire as at 11 is being wound in a plurality of turns about the coil form 10. The wire 11 is provided from a plurality of reels so as to develop a plurality of windings as at 11, 11a, etc., along the length of the coil form 10.

The wire 11, prior to being severed from winding a 3,358,175 Patented Feb. 6, 1968 previous coil form is taped as by the tape 12 to the outside of the coil form 10. Thereafter, a number of turns as at 13, 14, 15 and 16 are laid down on the coil form 10. When the wire 11 is in the configuration designated 16 and shown in phantom, the inventive anchor strip 17 (designated 17' in the phantom showing) is hooked around the wire 16' and moved into the position designated in solid line.

Advantageously, the side of the anchor strip 17 confronting the coil form 10 is equipped with an adhesive which may be of the water-soluble or pressure-sensitive type. Thereafter, the winding is continued with subsequent turns being developed as at 18, 19, 20, etc. These latter turns along with the remaining portion 16' of the turns 16 overlie the anchor strip with the turns 18-20, etc., overlying the tongue portion 21 of the strip 16 (see also FIG. 2.).

After the first layer of winding is completed, an insulating paper or film 22 is positioned over the winding. After this, the winding operation continues, the wire shuttling back and forth to provide a plurality of layers of the arrangement seen in FIG. 3. The remaining layers of winding generally terminate along a radial plane designated 23 in FIG. 3 defining the margin of the winding, and intermediate layers of winding are separated by in sulating paper as at 24 and 25.

The intial turns 13-16 are outside of the margin defined by radial plane 23 and thus are readily removed as at 26 to provide the inner lead of the coil form. In the past, the inner lead had to be picked from the tightly-wound layers of wire with the attendant danger of damaging the wire, or its insulation or of picking the wrong turn. The outer lead is developed in the usual manner by allowin g the final turn 27 to protrude beyond the outer wrapper 28 as at 29.

The configuration of anchor strip 17 is shown in FIG. 2. The strip is preferably made of high-grade kraft paper having a thickness of about 0.010 and a width of the order of about The strip 17 provides a wire-receiving slot generally designated 30 having a throat portion 31 and a slot portion or leg portion 32. The leg portion 32 is spaced equidistant the longitudinal sides of the strip 17 and the end of the leg portion is rounded as at 33 having a radius of curvature of approximately that of the wire 11. The throat-defining edge 34 extends inwardly towards the leg portion 32 at an angle of about 60 relative to the longitudinal edge 35 of the strip. The other side of the throat 31 is defined by the leading edges 36 and '37 of tongue 21. Leading edges 36 and 37 are beveled and have about the same slope as that of edge 24, i.e., about 60 relative to the longitudinal edge of the strip 17. The angles of the edges 34, 36 and 37 relative to the longitudinal edge may be increased up to about The beveled edges 36 and 37 of tongue 21 serve to prevent backwinding as the turns 16', 17, 18, etc., are wound over tongue portion 21 and eventually into slot 30. If the leading edge of tongue 21 were perpendicular to the longitudinal edge of strip 17, the last turn which is wound on tongue portion 21 would have a tendency to slide longitudinally towards the subsequent turn which occupies a portion of slot 30, thereby developing an undesirable hot spot. Beveling the end of tongue 21 allows the turns to slope gradually into the slot 30, substantially eliminating any tendency of backwinding. The first layer of winding terminates at about the forward end of transverse leg portion 32, as at 38, and the inclined edge 33 prevents the last turn of the first layer from being displaced longitudinally by the turns of the second layer, which overlies the first.

Through the use of a strip having an L-shaped slot 30 of the character described, I necessarily provide a tongue 2'1 sized to remain immobile even under the operation wherein the lead-providing margin turns 26 are moved longitudinally outward. This stems from the fact that a considerable number of turns overlay the tongue 21 and further, that when adhesive is present, this develops a superior contact surface for immobilizing the important area of the strip adjacent the turns which are withdrawn.

As the margin turn'26 and subsequent turns are pulled to provide the lead, the turn 16-16 is pulled against the strip at the rearward end of transverse leg portion 32 as at 33. If the end of the leg portion is not rounded and if the turn 16 is not pulled in a direction parallel to the longitudinal edge of the anchor strip, the wire will pull against the tongue and is apt to break off the tongue from the strip. Rounding the end of leg portion 32 insures that the pulling force exerted by turn 16 is distributed primarily against the full width of the anchor strip 17 rather than against either of the narrower portions on either side of the transverse leg portion.

The inventive anchor strip can also be used to provide intermediate leads which also may be easily removed from the layers of winding. Referring again to FIG. 3, the layer of winding designated 39 is wound from right to left. When this layer reaches the margin defined by radial plane 23, anchor strip 17a is hooked around a turn as previously described, and the winding is continued, the marginal turns overlying the strip. After insulating strip 40 is laid down, the next layer of winding is begun. When this layer reaches the margin, a second strip 17]) is hooked around the wire and the winding continues over the tongue portion of this strip. The strips 17a and 17b are firmly anchored by subsequent layers of winding, each of which is separated by insulation as at 41, 42, etc. The turns which provide the intermediate tap are outside the layers of winding and thus may be readily removed without having to pry a turn from between tightly-wound adjacent layers.

As mentioned previously, it is advantageous in some instances to equip the anchor strips 17 with an adhesive. When the anchor strip is constructed of kra ft, a watersoluble adhesive such as No. 476-425 of the Union Paste Co. of Hyde Park, Mass. is suitable. The anchor strip may also be constructed of ethylene terephthalate (Mylar), and in this case an adhesive such as No. S 396- available from B.B. Chemical Co. of Cambridge, Mass. may be used. For high-temperature work, is. coils used in high-temperature environments, the strip can be advantageously constructed of Nomexhaving a thickness of the order of 0.0075" with the adhesive layer being 0.002"-0.005" thick and here, I employ either of the foregoing pressure-sensitive or water-soluble adhesives.

While in the foregoing specifications a detailed embodiment of the invention has been set forth for the purpose of illustration, it is to be understood that many of the details hereingiven may be varied considerably by those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. A coil lead anchor strip comprising a uniform width elongated ribbon having a plurality of longitudinally spaced, generally L-shaped openings, each opening having a throat portion extending transversely inwardly from one longitudinal edge of said ribbon and a slot portion connection with said throat portion and forming in effect a right angled extension thereof and extending thereby longitudinally of said ribbon, said throat and slot portions defining an integral tongue for each L-shaped opening, one end of said tongue defining one edge of said throat, said tongue end being beveled and defined by angularly inclined sides having an included angle of between 120 and 160, the other edge of said throat portion extending at an angle of about to relative to said one longitudinal edge.

2. The strip of claim 1 in which the end of .said slot portion is rounded.

3. The strip of claim 1 in which said strip is constructed of kraft paper of about 0.010 inch in thickness.

4. The strip of claim 1 in which said strip is equipped with a pressure-sensitive adhesive.

5. A method of coil winding comprising winding a number of turns of conductor wire on a coil form, inserting around an extended portion of said wire an anchor strip, said anchor strip comprising a uniform width elongated ribbon having a plurality of longitudinally spaced generally Lshaped openings, each opening having a throat portion extending transversely inwardly from one longitudinal edge of said ribbon and a slot portion connection with said throat portion and forming in effect a right angle extension thereof and extending thereby longitudinally of said ribbon, said throat and slot defining an integral tongue for each L-shaped opening, said throat and slot portion being arranged in dimension relative to the longitudinal edges of said ribbon to provide said tongue with a length dimension at least one-half of the length of said slot portion, the length of said slot portion being measured along the slot portion edge remote from said one longitudinal edge, and continuing to wind wire over said strip and particularly the tongue portion thereof to mechanically anchor said strip in place on said coil form at least a portion of the turns underlying said strip being outside of the margin of the coil developed by said wire winding.

References Cited UNITED STATES PATENTS 2,122,894 7/1938 Sager 336192 2,985,950 5/1961 Duman. 3,153,214 10/1964 Brutt et al. 336-218 X R LEWIS H. MYERS, Primary Examiner.

T. ,T. KOZMA, Assistant Examiner. 

1. A COIL LEAD ANCHOR STRIP COMPRISING A UNIFORM WIDTH ELONGATED RIBBON HAVING A PLURALITY OF LONGITUDINALLY SPACED, GENERALLY L-SHAPED OPENINGS, EACH OPENING HAVING A THROAT PORTION EXTENDING TRANSVERSELY INWARDLY FROM ONE LONGITUDINAL EDGE OF SAID RIBBON AND A SLOT PORTION CONNECTION WITH SAID THROAT PORTION AND FORMING IN EFFECT A RIGHT ANGLED EXTENSION THEREOF AND EXTENDING THEREBY LONGITUDINALLY OF SAID RIBBON, SAID THROAT AND SLOT PORTIONS DEFINING AN INTEGRAL TONGUE FOR EACH L-SHAPED OPENING, ONE END OF SAID TONGUE DEFINING ONE EDGE OF SAID THROAT, SAID TONGUE END BEING BEVELED AND DEFINED BY ANGULARLY INCLINED SIDES HAVING AN INCLUDED ANGLE OF BETWEEN 120* AND 160*, THE OTHER EDGE OF SAID THROAT PORTION EXTENDING AT AN ANGLE OF ABOUT 60* TO 80* RELATIVE TO SAID ONE LONGITUDINAL EDGE. 